Sugar's 'tipping point' link to Alzheimer's disease revealed

Diabetes patients have an increased risk of developing Alzheimer's disease

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"Excess sugar is well known to be bad for us when it comes to diabetes and obesity, but this potential link with Alzheimer's disease is yet another reason that we should be controlling our sugar intake in our diets."

Dr. Omar Kassaar

For the first time, a "tipping point" molecular link between the blood sugar glucose and Alzheimer's disease has been established by scientists, who have shown that excess glucose damages a vital enzyme involved with the inflammation response to the early stages of Alzheimer's.

Abnormally high blood sugar levels, or hyperglycaemia, is well-known as a characteristic of diabetes and obesity, but its link to Alzheimer's disease is less familiar.

Diabetes patients have an increased risk of developing Alzheimer's disease compared to healthy individuals. In Alzheimer's disease abnormal proteins aggregate to form plaques and tangles in the brain which progressively damage the brain and lead to severe cognitive decline.

Scientists already knew that glucose and its break-down products can damage proteins in cells via a reaction called glycation, but the specific molecular link between glucose and Alzheimer's was not understood.

But now scientists from the University of Bath Departments of Biology and Biochemistry, Chemistry and Pharmacy and Pharmacology, working with colleagues at the Wolfson Centre for Age Related Diseases, King's College London, have unraveled that link.

By studying brain samples from people with and without Alzheimer's using a sensitive technique to detect glycation, the team discovered that in the early stages of Alzheimer's glycation damages an enzyme called MIF (macrophage migration inhibitory factor), which plays a role in immune response and insulin regulation.

MIF is involved in the response of brain cells called glia to the build-up of abnormal proteins in the brain during Alzheimer's disease. The researchers believe that inhibition and reduction of MIF activity caused by glycation could be the "tipping point" in disease progression. It appears that as Alzheimer's progresses, glycation of these enzymes increases.

"Excess sugar is well known to be bad for us when it comes to diabetes and obesity, but this potential link with Alzheimer's disease is yet another reason that we should be controlling our sugar intake in our diets," said Dr. Omar Kassaar of the University of Bath.

The study is published in the journal Scientific Reports.

Globally there are around 50 million people with Alzheimer's disease, and this figure is predicted to rise to more than 125 million by 2050. The global social cost of the disease runs into the hundreds of billions of dollars as alongside medical care patients require social care because of the cognitive effects of the disease.